Looper-thread controlling mechanism for sewing machines



Jan. 16, 1934. P. A. HERR '1,943,669

LooPEa THREAD coNToLLING MECHANISM FOR SEWING MA'HINES Filed Aug. 19, 1952 s sheets-sheet 1 gg I V P. A. HERR 1,943,669

LOOPER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Jan. 16, 1934.

Filed Aug. 19, 1932 3 Sheets-Sheet 2 Par/f Herr' Jan. 16, 1934. P. A, HERR 1,943,669

LOOPER 4THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed Aug. 19, 1932 3 Sheets-Sheet 3 gmc/wm Par/f JI. Herr' Patented Jan. 16, 1934 y f rFicE LOOPER THREAD CONTROLLING MECHA- NISM FOR SEWING MACHINES Park A. Herr, Hillside, N. J., assigner to The Singer Manufacturing Company, Elizabeth,

N. J., a corporation of New Jersey Application August 19, 1932.

Serial No. 629,416

14 Claims. (Cl. 112-241) This improvement relates to a thread controlling mechanism for sewing machines, more particularly of the chain-stitch type, and has for its object to provide a controlling device for the lower thread which will accomplish the delivery and the taking up of the lower thread to and from the` looper so that the thread will be under control at all times.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the sevveral features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 is a partial side elevation of the sewing machine,

T20 with the bed partly in section, and the needle in 3.0 bed 1, an upright standard 2, and overhanging head 3 in which the reciprocating needle-bar, carrying the needle 4, and the presser-bar 5, are ,mounted The presser-foot 6, carried by the .presser-bar, cooperates with a suitable four- '3.5 motion feed-dog 7 which operates through the usual slotted throat-plate 8 let in the cloth-plate `or work-support 9. It will be observed the upright standard 2 joins the bed l, close to the line of seam formation represented by the position of the needle 4 affording only a minimum of space for working parts beneath the work-support 9.

Cooperating with the needle 4, below the throat-plate 8 is the looper 10 having the heel 10l -and the blade 11. The looper 10 is mounted upon a carrier 12 whose lower end is journaled upon the pin 13 projecting forwardly from the split hub 14 clamped upon the rock-shaft 15 suitably journaled in bearing supports 16, 16 in the bed 1. The looper-carrier l2 is retained upon the pin 13 by the collar 17 clamped thereon by screws 18. Fixed upon the rock-shaft by the clamp-screw 19 is the forked arm or connection 20 straddling the slide-block 21 embracing an eccentric 22 fixed upon the main shaft 23 suitably journaled in the bed 1. The eccentric 22and the described connections therewith operate to rock the shaft 15 thereby imparting sidewise or so called needle-avoiding movements to the looper 10. 59

The looper derives its loop-seizing or endwise movements through a train of connections including a link 24 connecting the ball stud 25 on the looper-carrier 12 with a similar ball stud at the upper end of the arm 26 of a bell-crank lever @f5 fulcrumed at 27 upon the bed 1. The other arm 28 of the bell-crank lever is connected by a pitman 29 with a crank formed upon the main shaft 23.

The present looper-thread control is of the oscillatory type whereby the danger of winding up the looper-threadis avoided. Owing to the limited space between the looper and the junction of the bed and upright standard, the looperthread control must necessarily be Very compact. Mounted upon the driving connection or forkedarm 2G between the main shaft 23 and looper rock-shaft 15, is one element 30 of the looperthread control comprising coacting thread-engaging elements preferably of the thread-guide and thread-cam type. In the form illustrated the member 30 is the thread-guide member and is in the form of a fork, the arms of which are apertured at 31 to receive the looper-thread t. The shank of the thread-guide 30, is secured -8-5 upon the connection 20 by the fastening screw 32, and partakes of its oscillatory movements.

Cooperating with the oscillating thread-guide 3i) is the oscillating thread-cam 33 having the active portion or hump 34 which passes between the arms of the fork 30. The threadguides 3l and thread-cam 34 are in juxtaposed cooperative relationship, that is, the thread runs directly from one to the other, without engaging an intervening thread-guide of any sort. The 795 shank of the thread-cam is seated in a recess formed upon the follower 35 whose upper end embraces an eccentric 36 fast upon the main looper-blade ll, From the guide-eye 41 the looper-thread passes directly to the eyes 31 in the arms of the fork constituting the threadguiding member 30 and thence to the eye in the closely adjacent looper-blade 11. It will thus be seen that the looper-thread passes in a direct and straight path from the guide-arm 42 of the tension device to the looper-blade without deviating from its course which insures a free and unobstructed movement of under thread except where it is acted upon by the thread-controlling elements which are disposed closely adjacent the heel of the looper and work in planes transverse to the direction of its loop-seizing and shedding movement to control the looper-thread.

It will be observed by reference to Fig. 5 that the path of movement described by the thread-eyes 31 in the arms 30 is inthe arc of a circle represented by the dotted lines o described about the fixed axis of the looper rockshaft 15 as a center, while a point on the active portion 34 of the thread-cam describes the orbital path of movement around a eld represented by the dotted ellipse b.

'I'he operation of the device is substantially as followsz-Starting in the position of the parts shown in Fig. l, the looper is in its forward or loop-seizing movement and is about to enter the needle-thread loop. In its forward stroke the looper draws thread from its source of supply through the thread-eyes 38 and 41 and tension device 40. During this time the forward edge 34a of the thread-cam 34 is only slightly out of alignment with the eyes 31 of the threadguide 30 which assists the looper in its threaddrawing action, the thread riding over the central hump of the cam just before the time that the looper-blade has completed its loop-seizing movement. In the retractive movement of the looper the hump 34 of the cam is traveling along the upper portion of its elliptical path in the direction of the arrow, Fig. 5, the thread being in engagement with the rear edge 34b of the cam and the thread-eyes 31 moving in the opposite direction about the circular arc a away from the edge 34h. This insures a rapid take-up action on the looper-thread to take upv the slack between the eye of the looper and the last stitch during the first part of the retracting motion of the looper. The looper thread is thus kept closely under control so that the point of the descending needle may, with certainty, enter the triangle formed by the looper-thread, looperblade and needle-loop which is around the looper-blade at this time. This prevents buckling of the looper-thread and insures proper position of the looper thread-loop preparatory to the next descent of the needle.

By the means described, correct formation of the stitches is accomplished without the use of additional pull-off or nipping devices acting upon the lower-thread.

The invention is not to be understood as limited to the precise construction and arrangement of parts shown and described as various modifications within the scope and spirit of the invention will be suggested to those skilled in the art from the foregoing disclosure.

Having thus set forth the nature of the invention, what I claim herein is:-

1. A looper-thread controlling mechanism for sewing machines comprising a shaft, an eccentric mounted upon said shaft, an eccentric follower, a thread-cam carried by said follower, spaced thread-guides on opposite sides of and cooperating with said thread-cam and a second eccentric on said shaft connected to oscillate said thread-guides for controlling the slack in the looper-thread.

2. A looper-thread controlling mechanism for sewing machines comprising a shaft, an eccentric mounted upon said shaft, an eccentric follower, a thread-cam carried by said follower, a second eccentric mounted upon said shaft adjacent said rst eccentric, a follower therefor, a threadguide carried by said follower and actuated by said second eccentric said thread-guide being mounted in juxtaposed cooperative relationship with the said thread-cam for controlling the slack in the looper-thread.

3. A looper-thread controlling mechanism for sewing machines comprising a shaft, an eccentric mounted upon said shaft, an eccentric follower, a thread-cam carried by said follower, a second eccentric mounted upon said shaft, and a thread-guide actuated by said second eccentric, said eccentrics being relatively timed to move said thread-cam and thread-guide simultaneously in opposite directions.

4. A looper-thread controlling mechanism for sewing machines comprising a main shaft, a looper, a looper supporting shaft, a connection between said shafts for imparting operative movements to said looper, a thread-guide carried by said connection, and a movable threadcam actuated by said main shaft and cooperating with said thread-guide for controlling the slack in the looper-thread.

5. A looper-thread controlling mechanism for sewing machines comprising a main shaft, a needle and a cooperating looper, a 4movable forked arm having spaced thread-eyes, an oscillatory thread-controlling arm disposed between said spaced thread-eyes, and independent means for imparting relative movements to said forked 115 arm and thread-controlling arm for controlling slack in the looper-thread.

6. A looper-thread controlling mechanism for sewing machines, comprising a needle and a, cooperating looper, a movable arm having'120 spaced thread-eyes, a thread-controlling arm movable around a eld in a plane disposed between said thread-eyes, and means for imparting relative movements to said arms for controlling the slack in the looper-thread. `125 '7. A looper-thread controlling mechanism for sewing machines comprising a main shaft, a looper rock-shaft, a looper carried thereby, a connection between said main and 1'ock-shafts, closely adjacent said looper for imparting opera- -130 tive movements to the latter, spaced arms having thread-eyes carried by said connection, and means disposed between said looper and said connection cooperating with said spaced arms for controlling the slack in the looper-thread.

8. In a sewing machine in combination, a main shaft, a needle, feeding mechanism, a looper, a looper rock-shaft, a connection between said shafts parallel with the line of feed for imparting operative movements to said 140 looper, an arm carried by said connection and provided with spaced thread-eyes, and an oscillatory thread-arm cooperating with said thread-eyes for controlling the slack in they looper-thread. 1

9. In a sewing machine, in combination, an upright standard, a work-support, a feeding mechanism, a looper with an apertured blade and means for actuating the same, a thread ltension on the upright standard, a thread-guidel-50 on the upright standard disposed below the level of the work-support, a main-shaft, a threadcontrolling device comprising relatively movable thread-engaging members disposed in juxtaposed cooperative relationship below the worksupport and at the level of the looper-blade for controlling the slack in the looper-thread, and independent operative connections between said main-shaft and said thread engaging members.

10. A sewing machine having a reciprocatory needle, a thread-carrying looper, means for imparting loop-seizing and shedding movements to said looper, and a looper-thread controller comprising a pair of independently timed oscillatory thread-engaging members closely adjacent the heel of the looper and working differentially in planes transverse to the direction of loopseizing and shedding movement of the looper whereby the thread is led directly from the controller to the looper.

1l. A looper-thread controller comprising cooperating oscillatory thread-cam and threadguiding devices, one of said devices having a fixed axis of oscillation and the other of said devices having an orbital oscillatory movement said thread-guiding devices being located relative to said thread-cam to hold the thread in position to be acted upon by said thread-cam, and separately timed actuating means for operating said devices in timed relation to one another.

12. A thread-controlling mechanism for sewing machines comprising a shaft, a pair of eccentrics mounted upon said shaft, a follower for each of said eccentrics and a pair of coacting thread-engaging devices each carried by its respective follower' for controlling slack in the sewing thread.

13. A thread-controlling mechanism for sewing machines comprising a shaft, a pair of eccentrics mounted upon said shaft, a follower for each of said eccentrics and a pair of coacting thread-engaging devices each carried by a respective follower, one of said thread-engaging devices being mounted to move around a field and the other of said thread-engaging devices being adapted to movably position the thread suitably to be acted upon by the rst mentioned thread-engaging device in its movement around said field.

14. A thread-controlling mechanism for sewing machines comprising a shaft, a pair of eccentrics mounted upon said shaft, a follower for each of said eccentrics and a pair of coacting thread-engaging devices each carried by a respective follower, one of said thread-engaging devices being mounted to move around a field and the other of said thread-engaging devices being mounted to move in an arcuate path and position the thread suitably to be acted upon in its movement around said field.

PARK A. HERR. 

